T. K. Maity

Bio: T. K. Maity is an academic researcher from Indian Institutes of Technology. The author has contributed to research in topics: Dosimeter & Radiation. The author has an hindex of 2, co-authored 2 publications receiving 40 citations.

Effect of gamma radiation on optical and electrical properties of tellurium dioxide thin films

Abstract: Gamma radiation induced changes in the optical and electrical properties of tellurium dioxide (TeO2) thin films, prepared by thermal evaporation, have been studied in detail. The optical characterization of the as-deposited thin films and that of the thin films exposed to various levels of gamma radiation dose clearly show that the optical bandgap decreases with increase in the gamma radiation dose up to a certain dose. At gamma radiation doses above this value, however, the optical bandgap has been found to increase. On the other hand, the current vs voltage plots for the as-deposited thin films and those for the thin films exposed to various levels of gamma radiation dose show that the current increases with the gamma radiation dose up to a certain dose and that the value of this particular dose depends upon the thickness of the film. The current has, however, been found to decrease with further increase in gamma radiation dose. The observed changes in both the optical and electrical properties indicate that TeO2 thin films can be used as the real time gamma radiation dosimeter up to a certain dose, a quantity that depends upon the thickness of the film.

Effect of gamma radiation on electrical and optical properties of (TeO2)0·9 (In2O3)0·1 thin films

Abstract: We have studied in detail the gamma radiation induced changes in the electrical properties of the (TeO2)0·9 (In2O3)0·1 thin films of different thicknesses, prepared by thermal evaporation in vacuum. The current–voltage characteristics for the as-deposited and exposed thin films were analysed to obtain current versus dose plots at different applied voltages. These plots clearly show that the current increases quite linearly with the radiation dose over a wide range and that the range of doses is higher for the thicker films. Beyond certain dose (a quantity dependent on the film thickness), however, the current has been observed to decrease. In order to understand the dose dependence of the current, we analysed the optical absorption spectra for the as-deposited and exposed thin films to obtain the dose dependences of the optical bandgap and energy width of band tails of the localized states. The increase of the current with the gamma radiation dose may be attributed partly to the healing effect and partly to the lowering of the optical bandgap. Attempts are on to understand the decrease in the current at higher doses. Employing dose dependence of the current, some real-time gamma radiation dosimeters have been prepared, which have been found to possess sensitivity in the range 5–55 μGy/μA/cm2. These values are far superior to any presently available real-time gamma radiation dosimeter.

Influence of gamma ray irradiation and annealing temperature on the optical constants and spectral dispersion parameters of metal-free and zinc tetraphenylporphyrin thin films: A comparative study.

Abstract: In this work, we report on the effect of γ-ray irradiation and annealing temperature on the optical properties of metal-free tetraphenylporphyrin, H2TPP, and zinc tetraphenylporphyrin, ZnTPP, thin films. Thin films of H2TPP and ZnTPP were successfully prepared by the thermal evaporation technique. The optical properties of H2TPP and ZnTPP films were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light in the wavelength range from 200 to 2500 nm. The absorption spectra of H2TPP showed four absorption bands, namely the Q, B, N and M bands. The effect of inserting Zn atom into the cavity of porphyrin macrocycle in ZnTPP molecule distorted the Q and B bands, reduced the width of absorption region and influenced the optical constants and dispersion parameters. In all conditions, the type of electron transition is indirect allowed transition. Anomalous dispersion is observed in the absorption region but normal dispersion occurs in the transparent region of spectra. We adopted multi-oscillator model and the single oscillator model to interpret the anomalous and normal dispersion, respectively. We have found that the annealing temperature has mostly the opposite effect of γ-ray irradiation on absorption and dispersion characteristics of these films.

Effect of gamma irradiation on structural and optical properties of Cd2SnO4 thin films deposited by DC sputtering technique

Abstract: The structural and the optical properties of DC sputtered Cd 2 SnO 4 thin films before and after γ-irradiation (50–250 kGy) have been reported. The structural features of the as-deposited and γ-irradiation films are investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The optical constants of the as-deposited and γ-irradiation films have been obtained in the wavelength range 350–2000 nm by using spectrophotometric measurements at nearly normal incidence. The obtained optical constants were used to estimate the type of transition for the as-deposited and γ-irradiation thin films. In the normal dispersion region, the refractive index dispersion is discussed by using a single-oscillator model and Drude model. The single oscillator model is used to calculate the third-order nonlinear susceptibility, χ (3) . Also, the plasma frequency ( ω p ) and free carrier concentration ( N ) are also calculated.

An investigation of 60Co gamma radiation-induced effects on the properties of nanostructured α-MoO3 for the application in optoelectronic and photonic devices

Abstract: Gamma ray has sufficient energy to ionize and displace of atoms when interacts with optoelectronic and photonic devices that are placed at γ-radiation exposure environment, can be exposed to gamma radiation, resulting the alteration of the physical properties and hence the performances of devices. A comprehensive investigation of physical properties of the semiconductor materials under the influence of gamma radiation is essential for the effective design of devices for the application in the radiation exposure environment. In this article, a potential candidate for optoelectronic and photonic devices, orthorhombic MoO3 nanoparticles with average crystallite size of 135.31 nm successfully synthesized by hydrothermal method. Then, the properties of nanoparticles exposed to low (10 kGy) and high (120 kGy) absorbed dose of γ-rays from 60Co source were characterized by XRD, FESEM, FTIR and UV–Vis–NIR spectrophotometer and effects of absorbed doses was investigated for the first time. A significant change is observed in different physical properties of α-MoO3 nanoparticles after gamma exposure. The XRD patterns reveal the average crystallite size, intensity and the degree of crystallinity decrease for low dose (10 kGy) and increases for high dose (120 kGy). The calculated average crystallite size exposed to low and high doses are 127.79 nm and 136 nm, respectively. The lattice strain and dislocation density, however, shows the opposite trend of crystallite size with absorbed doses. This result is good evidence for the deterioration of crystallinity for low dose and improvement for high dose. The FESEM results reveal the significant effects of gamma doses on the micrographs of layered structure and on grain size. The optical studies disclose that band gap increases gradually from 2.78 to 2.90 eV, this behavior is associated with the reduction of electronic localized states. These results suggest that α-MoO3 nanoparticles could tolerate high doses of gamma radiation, making it a promising candidate for optoelectronic and photonic devices for γ-ray exposure environment applications.

Effects of gamma irradiations on structural and electrical properties of indium oxide thin films prepared by thermal evaporation

Abstract: Effects of gamma irradiations on structural and electrical properties of the post-annealed indium oxide thin films of thickness 750 nm, prepared by thermal evaporation in vacuum, were studied. The thin films, exposed to various levels of the gamma radiation dose, were characterized by XRD, SEM and I – V measurements. Results show that the average grain size and the degree of crystallinity increase with the gamma radiation dose up to a certain dose and decrease thereafter. Results also show that the conductivity increases with the gamma radiation dose up to the same value of the dose and decreases thereafter. The dislocation density, however, shows the opposite trend of the dose dependence.

Improved structural properties, morphological and optical behaviors of sprayed Cu2ZnSnS4 thin films induced by high gamma radiations for solar cells

Abstract: Cu2ZnSnS4 (CZTS) thin films have been synthesized by spray pyrolysis technique, deposited on glass substrates and then irradiated by high gamma radiations. Six gamma radiation doses have been applied: 10, 20, 30, 40, 50 and 100 kGy. The main objective of this work was to study the physical properties behavior of CZTS thin films under high gamma irradiation. Structural, optical and morphological properties of CZTS thin films were explored by X-ray diffraction, spectrophotometer and Scanning Electron Microscope, respectively. Structural analysis has shown that no noticeable changes have been occurred in the preferred orientation (112) or diffraction angles after gamma irradiation. Nevertheless, a significant increase in crystallite size from 52 to 79 nm has been observed after irradiation with 100 kGy gamma dose, which indicates a clear enhancement in crystalline structure. Certain optical parameters such as absorption and extinction coefficients (α(λ),K(λ)) have been only slightly affected, which indicate a radiation hardness of the CZTS thin films within the ionizing radiation range studied in this paper. Band gap energy of the irradiated thin films have been increased with the irradiation and reached 1.6 eV at 100 kGy gamma dose. Other optical parameters such as refractive index n(λ) and lattice dielectric constant (e) have been determined and analyzed. All these experimental results clearly showed that structural properties of CZTS films have been improved by gamma irradiation while the optical properties have been slightly changed, which is favorable for optoelectronic applications working near nuclear environments or even for outer space solar cells and instrumentation for high-altitude flight, where gamma radiations are abundant.